Down a Dusty Lane

Picking up on the mystery of how a massive Planet X could form beyond the outer confines of the Sun’s magnetic environment, as per my previous posts on the accretion of dust beyond the heliopause (1,2) and an exploratory scientific paper I published earlier in the year (3). I’m searching for evidence, or at least some educated guesswork, about whether interstellar medium beyond the heliosphere of stars might be sufficient over time to build up substantial, gaseous planets loosely bound to their parent star systems. Such planets might, I suggest, accumulate dust clouds and rings around them, undisrupted by the action of the solar wind trapped within the inner magnetic sphere of the solar system.

Even though this kind of accumulation could be gradually taking place over billions of years, creating a meaningful adjustment to the mass of a substantial planet over these kinds of time periods, it doesn’t seem likely that this kind of effect could take place if our current interstellar environment is anything to go by (although the unexpected presence of interstellar ‘fluff’ beyond the heliopause, described by NASA (4), and the intrusion of large grain particles into the outer solar system (5) do offer some evidence of what could be ‘out there’).

Last month, I looked at evidence of massive stars being aided in their development by the dumping of immense quantities of neighbouring nebula material onto them (6). I wondered whether a similar mechanism might also be happening in interstellar space at the planetary level, based upon globular frameworks of nebula materials (like gigantic molecular clouds, and the like).

Another promising dusty environment could be the dust lanes bordering the spiral arms of the Milky Way galaxy, which the Sun moves through periodically. Catastrophists looking at the destruction wreaked upon the Earth at the time of the demise of the dinosaurs 66 Myr ago are reconsidering an old hypothesis about the action of massive dust clouds upon the Sun (7). There has been speculation in the past that the periodic movement of the Sun through the dusty borderlands around the galaxy’s spiral arms might trigger ice epochs:

“…The passage of the solar system through a dust lane bordering a spiral arm of the Galaxy may cause a temporary variation of the sun’s radiation and thereby lead to an ice epoch on earth. Calculations show that the passage of the solar system through very dense clouds could produce conditions leading to a brightening of the sun, an increase in precipitation on earth, and consequent onset of an ice age. It can be estimated that since its origin, the sun has passed through a spiral arm some 50 times in all, and rough estimates of time and duration of the passages agree qualitatively with the general picture of the ice age periods.” (8)

The (disputed) idea that the Sun’s movement through spiral arms might be coincident with the onset of ice epochs has been explored by a number of scientific researchers (9, 10), and is known as the galaxy-ice age hypothesis. Various mechanisms have been offered to explain the cooling of the Earth, from cosmic radiation upon the Earth’s atmosphere ionising gas into cloud-forming plasma (11), to the soaking up of the Earth’s atmospheric oxygen by the interstellar clouds, bringing down its ozone layer dramatically (12).

Another idea along similar lines was that the Earth’s immediate space environment could be altered by the intrusion of dense interstellar matter into the solar system, pushing back the heliopause to a point actually within the Earth’s orbit, thus rendering Earth and most of the other planets into a particularly cloudy interstellar space for a while (13).

So, while this is all very interesting, what I’m focussed upon here is the nature of these passages through dense fields of interstellar dust.

So, while this is all very interesting, what I’m focussed upon here is the nature of these passages through dense fields of interstellar dust. Recent work on the iridium layer associated with the extinction event 66 mya that killed off the dinosaurs has indicated that the Earth was exposed to this cosmic material over a period perhaps as long as 8 Myr. The implication of this may be that the iridium may have been deposited during prolonged exposure to a gigantic molecular cloud (14). The encounter with this vast dark cloud would have led over time to climate change and mass extinctions.

The Ice Epochs are long-lived affairs, implying that the Sun’s immersion in these dusty environments is prolonged (the very scale of the spiral arms themselves implies similar). Thus ample opportunity exists for the accretion of spiral arm interstellar dust around massive solar system planets beyond the heliosphere. Bear in mind that the dust clouds themselves are massive enough to push the heliopause back, potentially exposing the outer solar system gas and ice giant planets to this material, too. Once the clouds have passed, as the Sun moves on through, the heliopause is restored to its rightful place, and the action of the solar wind can once again clear out the Sun’s inner sphere of influence. The dust and materials around the outer planets (Neptune, Uranus, Saturn, even perhaps Jupiter) previously gathered from the dust clouds during their incursion is thus largely removed.

But this same mechanism does not apply beyond the current heliopause. A massive Planet X could accumulate a great deal of dusty material around it, forming a nebula environment. There is no solar wind at that distance to clear it all up after the Sun has moved to clearer realms. A massive Planet X body could then slowly accrete the material into complex rotating rings, moons, asteroids, whatever.

The elephant in the room here is that we are currently at the back end of a 4 Myr Ice Epoch. If there is a correlation between these Epochs – as opposed to the fluctuating Ice Ages and inter-glacial periods within them (driven largely by the Milankovitch Cycles) – and the immersion of the solar system in immense dust clouds (whether present in the borderlands of spiral arms or not) then it should be true to say that a massive Planet X object has recently been exposed to just such an effect. One might expect, then, that this massive Planet X body would still have wrapped around it this accumulated nebula. This would effectively cloak Planet X from our sight, both visibly and in the infra-red spectrum.

No wonder, then, that this object is so difficult to observe, even when its gravitational presence is increasingly evident indirectly (15).